Physical and electrochemical properties of Li[Ni0.4CoxMn0.6-x]O-2 (x=0.1-0.4. electrode materials synthesized via coprecipitation

Abstract

Highly crystalline Li[Ni0.4CoxMn0.6-x]O-2 (x = 0.1-0.4) powders were synthesized from LiOH center dot H2O and coprecipitated [Ni0.4CoxMn0.6-x](OH)(2) (x = 0.1, 0.2, 0.3 and 0.4) hydroxides. In order to evaluate the impact of Co and Mn ratio on the structure, X- ray absorption near edge spectroscopy (XANES) and Rietveld refinement analyses of X-ray diffraction data were carried out. XANES results indicated that the Li[Ni0.4CoxMn0.6-x]O-2 (x = 0.1 - 0.4) consist of Ni2+, Co3+, and Mn4+ in the crystal structure. Rietveld refinement analysis of the Li[Ni0.4CoxMn0.6-x]O2 (x = 0.1 - 0.4) revealed that an increase of Co content decreases both lattice parameters of a and c axes simultaneously. An increase of Co content results in an increase of specific discharge capacity, but the corresponding operation voltages were slightly shifted to lower voltage. Decreases in electrochemically inactive tetravalent Mn content in overall metal compositions are one of the possible reasons for the lowering of onset exothermic reaction temperature as confirmed by differential scanning calorimetric experiments.